An eellike, jawless vertebrate with a round sucking mouth, formerly included in a group with the lampreys and hagfishes.→ Agnatha
- ‘The skeleton of cyclostomes furnishes far fewer taxonomic characters than that of the more complex cheilostomes.’
- ‘Data concerning key evolutionary invertebrate and vertebrate groups, the protochordates, chondrichthyes and cyclostomes, are essential to establish evolutionary patterns of the peptides.’
- ‘Similar structures described in other cyclostomes appear to indicate attachment to originally flexible substrates, particularly algae.’
- ‘The presence of a luteal like structure in cyclostomes has been observed but its function is still unclear.’
- ‘This extant species has erect jointed colonies, an articulated growth-form which seemingly evolved convergently with that of crisiid cyclostomes.’
Mid 19th century: from cyclo- + Greek stoma mouth.